Power Adjustment Research Articles

Local Oscillator Power Adjustment-Based Adaptive Amplification for Coherent TDM-PON With Wide Dynamic Range

Coherent technology is a promising solution for future 100-Gb/s and even 200-Gb/s single-wavelength time-division multiplexing passive optical network (TDM-PON) systems. One of the key issues for coherent TDM-PON is the upstream burst-mode amplification. The limited resolution of the analog-to-digital converter (ADC) makes it challenging to detect burst signals with widely varying power levels. Local oscillator (LO) power adjustment is a promising solution to this problem. In the present study, we verified the feasibility of LO power adjustment for adaptive amplification in a 200-G coherent TDM-PON system. We investigated the overall performance of the system under different implementation conditions, such as ADC sampling scales, TIA MGC mode control voltages, LO optical power levels, and the received optical power (ROP). Simulation and experimental results indicated that LO power adjustment can widen the dynamic range of the coherent PON system. As a proof of concept, we tested the system performance with continuous-mode signals and signals of isolated patterns with a burst-mode data frame. The dynamic range was extended to >30 dB via LO power adjustment, with 38- and 37-dB power budgets for 200-Gb/s/λ coherent TDM-PON continuous signals and signals of isolated patterns, respectively, after a 50-km standard single-mode fiber (SSMF).

Demonstration of PS-QAM Based Flexible Coherent PON in Burst-Mode With 300G Peak Rate and Ultra-Wide Dynamic Range

Coherent passive optical network (PON) has been proposed to support the next generation high-speed optical access network owing to the superior receiver sensitivity and thereby the extended power budget for 100 G-and-beyond. In addition, PON's flexibility and adaptability are gaining increasing interest. Flexible PON is believed to be a powerful solution in optimizing the overall capacity based on the available channel conditions, i.e., the optical path loss (OPL) and the associated signal-to-noise ratio and nonlinearity impairments of the different groups of optical network units. In this study, we demonstrate the rate-flexible coherent TDM-PON in burst-mode based on probabilistic-shaping (PS) QAM modulations and local oscillator (LO) power adjustment technology, achieving a 300G peak rate and ultra-wide dynamic range. The principle, the burst-mode frame generation as well as the burst-mode signal processing are discussed in detail. To indicate the overall performance of achievable capacity and flexibility, a new metric, namely, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dynamic-range and net-rate product</i> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DRNRP</i> ) is introduced as the indicator to show the optimized throughput. Finally, we experimentally demonstrated a flexible coherent TDM-PON in burst-mode based on 25-GBaud PS-QAMs with the dynamic range of >35-dB in back-to-back. A record <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DRNRP</i> up to 7,104 dB·Gbps was achieved in the current system with net data rate varying from 255-Gbits/s to 85-Gbits/s as the OPL varies over 20-km fiber transmission.

Microstructure and Property Evolutions of Q345B Steel during Ultrasonic Shot Peening

In this paper, the surface of Q345B steel was strengthened using ultrasonic shot peening (USP) technology. Through the adjustment of USP time, power and distance, the surface morphology, roughness and microhardness of the USPed samples were measured using scanning electron microscopy (SEM), energy dispersive analysis (EDS), a roughmeter and a microhardness tester. At the same time, the corrosion behavior of USPed samples was observed and analyzed using software simulation calculation and an immersion experiment on the dynamic polarization curve. Through tests and characterization, the influence of different USP process parameters on Q345B steel and the relationship between them were explored. The original intention of this research was to obtain better parameters to improve both the strength and corrosion resistance of the material. The results indicated that, with the increase in the USP time and power and the decrease in the USP distance, the surface roughness, the thickness of the deformed layer and the microhardness of the samples increased at first and then stabilized, and an obvious delamination phenomenon and chemical composition difference appeared between the deformed layer and the substrate. It was shown that a longer USP time and a shorter USP distance caused spalling and cracks on a substrate surface, resulting in the corrosion becoming more serious. However, with the increase in the USP power, the corrosion resistance of the sample improved.

Numerical Investigation on Reduction of Power Consumption and Improvement of Success Rate for Consensus in Multi‐Agent Systems over a Wireless Network Considering the Number of Agents

AbstractIn this paper, we investigate power adjustment for multi‐agent systems in a wireless network where communication range is limited. The approach in which communication range is dynamically changed is utilized so as to save power consumption. However, since drawback of this approach is that agents cannot expand their communication range, it causes that communication between agents tends to be disconnected. To overcome this problem, we propose two power adjustment methods. In the first method, communication range is temporarily expanded in accordance with the number of neighboring agents. In the second method, agents change their communication range by using information on the total number of agents and relative distance between an agent and the farthest neighboring agent. Through numerical simulation, we show that the proposed power adjustment methods reduce power consumption and improve success rate for consensus. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Assisting the mode-locking of a figure-9 fiber laser by thermal nonlinearity of graphene-decorated microfiber.

The self-starting performance of a figure-9 fiber laser is critically dependent on the phase shift difference between the counter-propagating beams. Herein, we propose an effective approach to dynamically control the phase shift difference in a figure-9 fiber laser by utilizing the thermal nonlinearity of graphene-decorated microfiber device. With the adjustment of the control laser power injected into the graphene-decorated microfiber, the self-starting mode-locked threshold of the figure-9 fiber laser can be attained in a flexible pump power range, i.e., from 300 mW to 390 mW. These findings demonstrated that the graphene-decorated microfiber could act as a dynamical control device of phase shift difference for improving the performance of figure-9 fiber lasers, and might also open up new possibilities for applications of microfiber photonic devices in the field of ultrafast optics.

CEOs' Structural Power, Prestige Power, and Dynamic Target Adjustments

CEOs' Structural Power, Prestige Power, and Dynamic Target Adjustments

Infrared thermal wave detection of interfacial debonding defects of thermal barrier coatings based on non-linear frequency modulation

In order to improve the reliability of detecting the debonding defects at the interface of thermal barrier coatings (TBC), a non-linear frequency modulated (NLFM) infrared thermal wave detection method is proposed. A NLFM infrared thermal wave detection system is built, and zirconia TBC specimens are prepared and tested. The effects of defect diameter, excitation power, initial frequency and termination frequency on the defect detection effect are analyzed. Three algorithms such as principal component analysis (PCA) are used to process the image sequence, and the signal-to-noise ratio (SNR) of each sequence processing algorithm is calculated and compared. The results show that the larger the diameter of the defect, the easier it is to be detected, and the appropriate adjustment of the excitation power or the reduction of the initial and termination frequencies is beneficial to the detection of defects. Compared with the other two algorithms, the PCA method is more effective for image sequence processing. It offers a reference for detecting debonding flaws at the TBC interface.

A Blockchain-Enabled Demand Management and Control Framework Driven by Deep Reinforcement Learning

The rapid development of Internet-of-Things in smart grid has enabled millions of grid-connected distributed controllable resources (DCR; e.g., electric vehicles, controllable loads) to provide service to the grid, such as frequency regulation and demand response. The integration of these DCRs may become a large virtual power plant network with various characteristics. This poses great challenges from both control and management perspectives, e.g., computation/communication burden, optimization complexity, scalability limitation, prosumer privacy, etc. In this article, we propose an effective autonomous incentive-based DCR control and management framework to integrate a large amount of DCRs to provide grid services, which simultaneously provides accurate active power adjustment to the grid, optimizes DCR allocations, and maximizes the profits for all prosumers and system operators. A model-free deep deterministic policy gradient-based method is designed to find the optimal incentives in a continuous action space to encourage prosumers to adjust their power consumptions. The method is implemented in a consortium open-source blockchain platform, Hyperledger Fabric, which facilitates controls and transaction management. To demonstrate the effectiveness of the framework, extensive experimental studies are conducted using real-world data.

An Adaptive Energy Efficient MAC Protocol for RF Energy Harvesting WBANs

Continuous and remote health monitoring medical applications with heterogeneous requirements can be realized through wireless body area networks (WBANs). Energy harvesting is adopted to enable low-power health applications and long-term monitoring without battery replacement, which have drawn significant interest recently. Because energy harvesting WBANs are obviously different from battery-powered ones, network protocols should be designed accordingly to improve network performance. In this article, an efficient cross-layer media access control protocol is proposed for radio frequency powered energy harvesting WBANs. We redesigned the superframe structure, which can be rescheduled by the coordinator dynamically. A time switching (TS) strategy is used when sensors harvest energy from radio frequency signals broadcast by the coordinator, and a transmission power adjustment scheme is proposed for sensors based on the energy harvesting efficiency and the network environment. Energy efficiency can be effectively improved that more packets can be uploaded using limited energy. The length of the energy harvesting period is determined by the coordinator to balance the channel resources and energy requirements of sensors and further improve the network performance. Numerical simulation results show that our protocol can provide superior system performance for long-term periodic health monitoring applications.

2.4GHz Wireless Local Area Network Optimization in University Dormitory Buildings

This article describes the wireless network problems met in University dormitory buildings, especially under 2.4GHz spectrum. Through wireless network optimization such as channel re-allocation and transmission power adjustment manually, the performance of the wireless LAN could be improved a lot even for real-time services such as video and live broadcast.

Underwater Real-time Video Transmission via Wireless Optical Channels with Swarms of AUVs

Underwater wireless optical communication (UWOC) has received widespread attention recently due to its distinct advantages in terms of high bandwidth, low power consumption, low delay and confidentiality. However, unlike underwater acoustic communication systems, it suffers from constraints, such as limited communication range and misalignment in oceanic extreme environments. To perform long-distance high bandwidth transmission such as real-time video streaming, it requires relaying technology to perform reliable and robust transmission. Although pre-deploying a large number of sensor nodes is one of the possible solutions, this is impractical in response to emergency events, such as oil pipeline leakage and maritime search and rescue. To this end, in this paper, we propose to leverage a swarm of autonomous underwater vehicles (AUVs) to establish reliable underwater optical communication links in a rapidly changing marine environment for real-time video transmission. We first model the optical transmission channel, and then calculate both the optical angle and the reliable communicating range that satisfy a pre-defined bit error rate (BER). We then formulate the optimization problem based on two aligned solutions while targeting on minimizing both deployment energy consumption and time latency, in which the AUV's uncertainty issue caused by localization error and hovering instability is considered. Finally, we design an adaptive optical beam and power adjustment algorithm to enhance the robustness of the optical link further. Through extensive simulations, the results demonstrate that the proposed scheme is efficient and achieves reliable and robust communication.

A Practical Approach to Cosmetic Tattoo Removal with the Nd:YAG Laser.

The Q-switched neodymium-yttrium aluminium garnet (Nd:YAG) laser remains the gold standard method for tattoo removal including cosmetic tattoos. Modern picosecond lasers are referenced to the Nd:YAG laser and essentially do the same job. Persons with cosmetic tattoos in the face are especially eager to achieve perfect removal or correction and from start are critical to suboptimal results. Customers mostly request complete removal; sometimes the goal is fast treatment and bleaching to prepare for a cover up tattoo. Removal or correction of eyebrows is the largest group, followed by lip tattoos and eyeliners. The article gives a systematic and stepwise introduction to routine cosmetic tattoo removal by laser in an Austrian private medical practice. Rationales and selection of customers who can benefit from treatment, preparation, performance, and aftercare is reviewed. Emphasis is given to qualified power adjustment of the laser equipment and the treatment strategy, e.g. the delicate navigation between efficient removal and the risk of short-term and long-term adverse effects. Treatment relies on a partnership between provider and customer. Over the months of treatment, customers gain more insight into the possibilities of treatment, so that they get an understanding of the realistic results that can be achieved. Therefore, customers are also satisfied even with results that are not always optimal since best treatment was given a fair chance.

Accuracy of Intraocular Lens Power Calculation in Pediatric Secondary Implantation: In-the-Bag Versus Sulcus Placement

To compare the effects of secondary in-the-bag vs ciliary sulcus intraocular lens (IOL) implantation on the accuracy of IOL power calculation in pediatric eyes. Prospective nonrandomized interventional study. Pediatric aphakic eyes that underwent either in-the-bag or ciliary sulcus secondary IOL implantation were included. The mean prediction error (PE), mean absolute error (MAE), median absolute error, and percentages of eyes with PE within ±0.25 diopter (D), ±0.50 D, ±0.75 D, and ±1.00 D were calculated and compared using SRK/T formula. One hundred fourteen eyes (38.26%) received in-the-bag IOL implantation and 184 (61.74%) underwent ciliary sulcus IOL implantation. Compared with the sulcus group, the capsular group displayed significantly lower MAE and higher percentage of eyes within ±0.50 D of PE (MAE: 0.90 vs 1.56 D; ±0.50 D: 40.40% vs 14.29%, both P < .001). The eyes receiving in-the-bag IOL implantation (sulcus IOL implantation β: -1.060, 95% CI: -1.415 to -0.705; P < .001), unilateral (β: 0.647, 95% CI: 0.144-1.150; P=.012), or with deeper anterior chamber depth (β: 0.362, 95% CI: 0.068-0.656; P=.016) were prone to maintain hyperopia (PE > 0). To reduce PE, when the predicted capsular IOL power was between 11.50 and 30.00 D, the power of a sulcus-implanted IOL should be reduced by 0.50 to 2.50 D accordingly (the exact amount of reduction is positively related to the predicted power). In-the-bag implantation yielded smaller PE in pediatric eyes undergoing secondary IOL implantation. Adjustment of IOL power for ciliary sulcus implantation is required to reduce PE, and the amount of adjustment is positively correlated with the IOL power predicted by SRK/T formula.

Residential power scheduling based on cost-coupling constraint with distributed generation

Power scheduling is a major task for demand response (DR) to cope with the electricity consumption during the peak period in smart grid. In the residential sector, consumers trend to trigger their electrical appliances when the electric price is low. However, power scheduling including load curtailment, time delay and equipment power adjustment will change consumer’s comfort level to produce discomfort cost. Thus, electricity payment and discomfort cost are coupled to constraint the DR. In this paper, we focus on renewable energy use by smart homes and consider cost-coupling constraints, taking an approach whereby we decouple the primary problem into several independent subproblems. A novel DR algorithm based on cost-coupling constraint with distributed generation is developed to reduce consumers’ expenditure while improving their comfort. To that end, a day-ahead bidding price mechanism including real-time charging management is introduced, and a cost efficiency algorithm is designed based on electricity payments, discomfort and distributed generation. Simulation results demonstrate that the proposed method is effective and feasible when tested in real application scenarios.

Inertial imitation method of MMC with hybrid topology for VSC-HVDC.

A new virtual synchronous generator (VSG) control strategy was researched and proposed for a VSC-HVDC (High Voltage Direct Current Based on Voltage Source Converter) transmission system. It can be applied to half-bridge or full-half-bridge hybrid topology modular multi-level converter (MMC) to improve the stability and reliability of the system. First, it is proposed that the energy stored in the equivalent capacitor of MMC power module was used to imitate the rotor inertial of synchronous generator. It can buffer transient power fluctuations and synchronize autonomously with the grid. Then the impedance characteristics of the proposed control method have been deduced and analyzed. The results show that the VSG control loop mainly improves the low frequency characteristics of the converter. Secondly, the ability to suppress transient fault current is weak. So, a method, that the given values of inner current loop are calculated by grid impedance matrix, was used. A double closed loop control structure composed by a power outer loop based on VSG control and a current inner loop is obtained. The simulation results show that it can effectively improve the current control capability during the transient process for systems with a 1:2 ratio of converter capacity to grid capacity (The grid short-circuit capacity is 60MW and the MMC is 30 MW). Finally, a hybrid MMC simulation model was built based on PSCAD and the steady-state and transient fault ride-through simulations were performed. The power adjustment time of MMC under the proposed VSG control is about 1s, while the adjustment time under the conventional control strategy is greater than 4s.

Single and Multiple Pulse Pattern Formation in All-Normal All-PM Yb-Doped Fiber Laser Using a Nonlinear Optical Loop Mirror

We report the evolution of single-pulse and multi-pulse in a mode-locked all polarization-maintaining fiber laser based on a nonlinear optical loop mirror (NOLM). The main parameters of the laser were determined by numerically simulating the relationship between the number of pulses and the basic parameters of each element. Experiments demonstrate generation of 1 to 6 pulses per cavity round trip. There is an unstable regime between the stable N and N + 1 pulses states when gradually increasing the pump power, while the intervals of the unstable regime shrink or even disappear when the direction of pump power variation is reversed. Our experimental results are different from those previously reported where the intervals of the unstable pulse regime are almost unchanged regardless of the pump power adjustment direction. We also describe how to obtain fundamental mode-locking from the multi-pulse state. The laser operated in the single-pulse regime shows excellent stability.

Reactive power control and performance analysis of doubly fed induction generatorin micro grid

For both financial and environmental considerations, the power system includes a large number of solar and wind generating plants. In reality, wind energy has always been used using a doubly fed induction generator (DFIG) based variable speed wind turbine. This study examines the effectiveness of indirect control of a doubly fed induction generator for closed loop reactive power adjustment. A wind energy conversion system with continuous grid power's design, analysis, and MATLAB simulation are also covered. For DFIG to work reliably and be controlled to ensure stability for the power system, a seamless transition mode change is required. The horizontal axis wind turbine technology provides the necessary reactive power into the grid under all unexpected circumstances. The concept of DFIG mathematical modelling is covered. Various simulated outputs at loading circumstances are shown, along with separate control of active and reactive powers and variations in prime mover speed and excitation. This study examines the performance enhancement of DFIG using its grid-based proportional integral (PI), proportional integral derivative (PID), and fractional order proportional integral derivative (FOPID) controllers. Based on the thorough simulation findings, the type of control system that gives the efficient performance of DFIG in grid is ultimately decided. These simulation results demonstrate how the suggested controllers outperform the current controllers in terms of improving system performance.

Energy management method of integrated energy system based on collaborative optimization of distributed flexible resources

Under the background of energy internet and low-carbon power, integrated energy system (IES) has become an important carrier of energy conservation and emission reduction. The IES utilizes innovative energy management mode to coordinate various energy sources such as natural gas, electric energy and heat energy. It is composed of energy production, conversion, storage and consumption subsystems, which emphasizes breaking the isolation of energy subsystems through reasonable scheduling, realizing energy cascade utilization and improving energy utilization efficiency. In this paper, an energy management model with two-stage scheduling before day and in real time is proposed aiming at the collaborative optimization of generator-load-storage of IES. Firstly, the first stage is the day-ahead economic dispatch, which aims to realize the power distribution of units in the system. The day-ahead economic dispatching model takes the maximization of economic benefits, the maximization of exergy efficiency and the minimization of carbon emission cost as the optimization objectives, so as to make the day-ahead global optimal dispatching decision. Secondly, the second stage is real-time optimal scheduling, which aims at real-time power adjustment of the previous scheduling plan. The real-time optimal scheduling model takes the minimum interactive power deviation punishment cost, wind abandonment punishment cost and user satisfaction loss cost as optimization objectives, so as to balance the energy supply and load demand deviation between planned output and actual output. Thirdly, according to the characteristics of the model, Non-dominated Sorting Genetic Algorithm-II (NSGA-II) is used to solve the first-stage day-ahead economic scheduling, and YALMIP toolbox is used to solve the real-time optimal scheduling model. Finally, based on the established model, a typical IES is selected for case simulation, which verifies that the proposed method can effectively improve the economy of system operation.

Lower-Limb Muscle Power Is Negatively Associated with Protein Intake in Older Adults: A Cross-Sectional Study.

The present study examined the association between lower-limb muscle power and protein-related parameters in older adults. This study followed a cross-sectional design. Participants were community-dwelling older adults. Candidates were considered eligible if they were 60 years or older, lived independently, and possessed sufficient physical and cognitive abilities to perform all the measurements required by the protocol. The 5 times sit-to-stand (5STS) test was performed as fast as possible according to a standard protocol. Absolute, relative, and allometric muscle power measures were estimated using 5STS-based equations. Diet was assessed by 24-h dietary recall and diet composition was estimated using a nutritional software. One-hundred and ninety-seven older adults participated to the present study. After adjustment for covariates, absolute and allometric muscle power were negatively associated with body weight-adjusted protein intake. Our findings indicate that absolute and allometric muscle power estimated through a simple equation are negatively associated with body weight-adjusted protein intake in community-dwelling older adults.

Enhanced Dynamic Performance in Hybrid Power System Using a Designed ALTS-PFPNN Controller

The large-scale, nonlinear and uncertain factors of hybrid power systems (HPS) have always been difficult problems in dynamic stability control. This research mainly focuses on the dynamic and transient stability performance of large HPS under various operating conditions. In addition to the traditional synchronous power generator, wind-driven generator and ocean wave generator, the hybrid system also adds battery energy storage system and unified power flow controller (UPFC), making the system more diversified and more consistent with the current actual operation mode of the complex power grid. The purpose of this study is to propose an adaptive least squares Petri fuzzy probabilistic neural network (ALTS-PFPNN) for UPFC installed in the power grid to enhance the behavior of HPS operation. The proposed scheme improves the active power adjustment and dynamic performance of the integrated wave power generation and offshore wind system under a large range of operating conditions. Through various case studies, the practicability and robustness of ALTS-PFPNN method are verifying it by comparison and analysis with the damping controller based on the designed proportional integral differential (PID) and the control scheme without UPFC. Time-domain simulations were performed using Matlab-Simulink to validate the optimal damping behavior and efficiency of the suggested scheme under various disturbance conditions.